As fabrication techniques for semiconductor integrated circuits continue to develop, the number of elements in a chip has increased. High aspect ratio fin structures were key elements to achieve required cell capacitance in the fabrication devices. However, after various kinds of aqueous processing of silicon wafers, residual moisture may be remained on the surface of wafers, thereby interfere the procedures in advance and induce defects; thence the wafers need to be dehydrated after aqueous processes in order to alleviate the defects on fin structures caused by residual moisture.
Conventionally, the dehydration process includes spinning the wafer at high speed, as the water can be spun off the wafer edge by centrifugal force. However, the fin structures with high aspect ratio are weak and prone to be damaged throughout the process of spinning due to the surface tension applied by water on the fin structures. The pattern of the fin structures may collapse and induce defect after dehydration processes. Furthermore, the collapsed fin structures cannot be effectively recovered hitherto.
According to Young-Laplace equation, the Laplace pressure between an air-liquid interface has a positive correlation with surface tension, contact angle, and distance between two given fin structures. Meanwhile the pattern deflection has a positive correlation with pattern height, aspect ratio, contact angle, and Laplace pressure. Therefore surface tension and contact angle are two of the major factors to be solved pertinent to pattern deflection.